Articles incorporating fluorescent colorants into polymeric matrices can be used for various applications including signage, vehicle markings, roadway markings, and other applications where high visibility is desired, such as information dissemination, visibility, visual signaling, and quick detection. The extraordinarily bright appearance of fluorescent materials is what provides this enhanced visibility, which is especially pronounced at dawn and dusk.
Fluorescent colorants that can be potentially used in outdoor signage can have poor UV-light stability and can fade upon exposure to certain wavelengths of visible light. This can potentially degrade the long-term outdoor durability of the signage. A UV-light screening layer can be provided on a base fluorescent polymer matrix layer to mitigate exposure to UV-light and enhance outdoor durability. The UV-light screening layer can be made by dissolving UV-light absorbing compounds into a transparent polymer matrix. U.S. Pat. No. 5,387,458 and Japan Patent Publication No. 2-16042 (Application No. 63-165914) disclose fluorescent articles consisting of an ultraviolet light screen layer disposed in front of a fluorescent color layer. The screen layer contains UV absorbing compounds that absorb a defined range of UV-light (e.g., wavelength of about 290 nm to about 400 nm). The screen layer, however, does not substantially block visible light that can cause substantial fading of fluorescent colorants in the polymer matrix.
To date, fluorescent colorants are available in only a limited range of hues. For example, fluorescent colorants are commercially available in hues, such as fluorescent red, fluorescent orange, fluorescent pink, and fluorescent yellow-green. A fluorescent yellow that meets the chromaticity requirements of the Commission Internationale de l'eclairage (CIE) and the Federal Highway Administration (FHWA) is not readily available.